Yield:32184-10-4 86%

Reaction Conditions:

with manganese(IV) oxide;bromine in dichloromethane at 20; for 3 h;Reagent/catalyst;Time;

Steps:

Typical example procedure for radical reaction on bromination of N-acetyl-N-(2,4-dibromo-6-methylphenyl)acetamide with MnO2/Br2

IIa (1.0 mmol) was dissolved in dichloromethane (10 mL). Commercially available non-activated MnO2 (2.0 mmol) was added first and then liquid bromine (1.0 mmol) in 5 mL dichloromethane was added dropwise over a period of 2 h under vigorous agitationat ambient temperature using an ambient temperaturewater bath. The entire progress of the reactionwas monitored by TLC. After 1 h the reaction was quenched by the addition of water (20 mL) and the precipitated MnO2 was filtered and washed with dichloromethane (10 mL). The combined organic phase was washed to neutral reaction and dried over anhydrous Na2SO4. The solvent was evaporated under reduced pressure and a brown solid was formed. The crude product (3.50 g, yield of 92 %) was purified by recrystallisation from hexane (30 mL) and white needles were obtained. N-acetyl-N-(2,4-dibromo-6-(bromomethyl)-phenyl)-acetamide (III). White needle crystals; yield 3.67 g (86 %), m.p. 118.2-119.4° C; 1H NMR (CDCl3, 500 MHz), δ: 2.38 (s, 6H, 2 × -COCH3), 4.26 (s, 2H, -CH2Br), 7.67 (d, J= 2.1 Hz, 1H, -ArH), 7.84 (d, J = 2.1 Hz, 1H, -ArH); 13C NMR (CDCl3, 125 MHz), δ: 26.4, 27.5, 123.6, 125.5, 133.8, 136.3, 136.6, 139.1, 171.9. MS (m/z, ESI): 427.490 [M + H]+ (calc. for C11H11Br3NO2, 427.493). Elemental analysis calculation for C11H10Br3NO2, C,30.87; H, 2.36; N, 3.27; found: C, 31.00; H, 2.45; N, 3.15

References:

Xu, Jun-Hui;Ma, Yan-Qiong;Wei, Jian-Ping;Li, Fang-Mei;Peng, Xin-Hua [Chemical Papers,2015,vol. 69,# 5,p. 722 - 728]